• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.866-873
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• 2009

CFRD (Concrete Faced Rockfill Dam) has been world-widely constructed due to a lot of advantages compared with rockfill dam and recently, sand/gravel materials, instead of crushed rock materials, are also utilized as a main rockfill material to overcome geological and environmental problems. In this paper, the process of water infiltration into the originally unsaturated sand/gravel-fill dam is studied using two-dimensional saturated-unsaturated seepage theory. According to the results of seepage analysis, if the effective drainage zone is installed in the dam, the reservoir water infiltrate into the dam along a downward flow path towards the lower drainage area. The main body constructed with sand/gravel materials, therefore, remains unsaturated.

• The Journal of Engineering Geology
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• v.15 no.1
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• pp.77-86
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• 2005

CFRD(Concrete Faced Rockfill Dam) is in widespread use because this type of dam has superior characteristics in structural, material aspects comparing with earth cored rockfill dam. On this paper, up-to-date re-searches and techniques are summed up to be available for future needs in design and construction of CFRD. For example, such items as embankment using weak rock, experience of sand-gravel fill CFRD, connecting slab applied between plinth and face slab, raising experience of old dm, inverse filtration problem, environmental friendly zone, thickness and reinforcing of face slab, alluvial foundation treatment, and curb element method, are summarized for understanding of related engineers.

• Geomechanics and Engineering
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• v.14 no.3
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• pp.211-224
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• 2018

In this paper, a predictive method accounting for the scaling effects of rockfill materials in the numerical deformation analysis of rockfill dams is developed. It aims to take into consideration the differences of engineering properties of rockfill materials between in situ and laboratory conditions in the deformation analysis. The developed method is based on the modification of model parameters used in the chosen material model, which is, in this study, an elasto-plastic model with double yield surfaces, i.e., the modified Hardening Soil model. Datasets of experimental tests are collected from previous studies, and a new dataset of the Nam Ngum 2 dam project for investigating the scaling effects of rockfill materials, including particle size, particle gradation and density, is obtained. To quantitatively consider the influence of particle gradation, the coarse-to-fine content (C/F) concept is proposed in this study. The simple relations between the model parameters and particle size, C/F and density are formulated, which enable us to predict the mechanical properties of prototype materials from laboratory tests. Subsequently, a 3D finite element analysis of the Nam Ngum 2 concrete face slab rockfill dam at the end of the construction stage is carried out using two sets of model parameters (1) based on the laboratory tests and (2) in accordance with the proposed method. Comparisons of the computed results with dam monitoring data indicate that the proposed method can provide a simple but effective framework to take account of the scaling effect in dam deformation analysis.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.653-656
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• 2008

The main purpose of this research was to enhance the durability in both the design and construction of dams. Especially, in case of rockfill dams, the durability of face slab concrete in a concrete-faced rockfill dam(CFRD) is achieved by optimizing the fly ash replacement for cement and application of blended fiber. The effect on durability and thermal property corresponding to the increasing replacement of fly ash and application of blended fiber was evaluated, and the optimum value of fly ash replacement and blended fiber application was recommended. The results show that 15% of fly ash replacement and 0.9kg/m3 of blended fiber application was found to be an optimum level and demonstrated excellent performance in durability and thermal property.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.679-682
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• 2005

The effects of substituting cement with fiber addition(poly vinyl alcohol), fly ash and Expansive Additive on the control of microcrack and enhanced durability performance of face slab concrete in concrete-faced rockfill dam was studied experimentally The laboratory test results shown that the mixture of fiber containing concrete and of fly ash replacement of concrete to be more effective than expansive additive concrete in the crack control and mechanical performance.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.871-876
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• 2010

When surface Concrete Face Rock fill Dam constructs than existent center core type rock fill dam, it is much prevalent form in domestic these day by quality control of that is profitable and weather condition etc. of coreZone. C.F.R.D is less research about seismic survey(Refractional Seismic Prospectin, Resistivity Prospecting) of levee body than fill dam. Thus as C.F.R.D seismic survey is less, safety of that consist is short most development flue is high reason. That is not checking target of minuteness safety diagnosis and so on by short operation period. Wish to analyze inquiry incidental and difference with center core type dam and acquire C.F.R.D preservation administration upper necessary inquiry condition forward hereafter.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.1017-1022
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• 2001

Dam concrete for pumped storage power plants should have sufficient durability in repetitive wet and dry conditions and abrasion due to water level fluctuation and also in freezing and thawing resistance as well as permeability capacity. This study presents various experimental results to enhance the durability of face slab concrete in CFRD(concrete faced rockfill dam) by varying the fly ash substitution such as 0%, 15%, 20% and 25% and polypropylene such as 0%, 0.1%. The effect on durability of concrete corresponding to the increasing amount of fly ash and polypropylene was evaluated and the optimum quantity of fly ash and polypropylene substitution was recommended. The results show that 20% of fly ash substitution and 0% of polypropylene were found out to be an optimum quantity to achieve excellent performances in durability for face slab concrete in CFRD.

• Earthquakes and Structures
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• v.16 no.2
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• pp.221-234
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• 2019

Today, many important concrete face rockfill dams (CFRDs) have been built on the world, and some of these important structures are located on the strong seismic regions. In this reason, examination and monitoring of these water construction's seismic behaviour is very important for the safety and future of these dams. In this study, the nonlinear seismic behaviour of Ilısu CFR dam which was built in Turkey in 2017, is investigated for various reservoir water heights taking into account 1995 Kobe near-fault and far-fault ground motions. Three dimensional (3D) finite difference model of the dam is created using the FLAC3D software that is based on the finite difference method. The most suitable mesh range for the 3D model is chosen to achieve the realistic numerical results. Mohr-Coulomb nonlinear material model is used for the rockfill materials and foundation in the seismic analyses. Moreover, Drucker-Prager nonlinear material model is considered for the concrete slab to represent the nonlinearity of the concrete. The dam body, foundation and concrete slab constantly interact during the lifetime of the CFRDs. Therefore, the special interface elements are defined between the dam body-concrete slab and dam body-foundation due to represent the interaction condition in the 3D model. Free field boundary condition that was used rarely for the nonlinear seismic analyses, is considered for the lateral boundaries of the model. In addition, quiet artificial boundary condition that is special boundary condition for the rigid foundation in the earthquake analyses, is used for the bottom of the foundation. The hysteric damping coefficients are separately calculated for all of the materials. These special damping values is defined to the FLAC3D software using the special fish functions to capture the effects of the variation of the modulus and damping ratio with the dynamic shear-strain magnitude. Total 4 different reservoir water heights are taken into account in the seismic analyses. These water heights are empty reservoir, 50 m, 100 m and 130 m (full reservoir), respectively. In the nonlinear seismic analyses, near-fault and far-fault ground motions of 1995 Kobe earthquake are used. According to the numerical analyses, horizontal displacements, vertical displacements and principal stresses for 4 various reservoir water heights are evaluated in detail. Moreover, these results are compared for the near-fault and far-faults earthquakes. The nonlinear seismic analysis results indicate that as the reservoir height increases, the nonlinear seismic behaviour of the dam clearly changes. Each water height has different seismic effects on the earthquake behaviour of Ilısu CFR dam. In addition, it is obviously seen that near-fault earthquakes and far field earthquakes create different nonlinear seismic damages on the nonlinear earthquake behaviour of the dam.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.415-420
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• 1999

Dam concrete should have sufficient durability in wet and dry repetition and abrasion due to water lever variance and also in freezing and thawing resistance as well as water penetration capacity. This study presents various experimental performance to enhance the durability of face slab concrete in concrete face rockfill dam by varying the fly ash substitution of 0%, 10%, 15% and 20% in cement quantity. The effect on durability corresponding to the increasing amount of fly-ash was evaluated and the optimum quantity of fly-ash subtitution was finally recommended. The results show that 15% fly-ash substituion was found out to be an optimum quantity and demonstrated an excellent performances in durability.

• Geotechnical Engineering
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• v.12 no.1
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• pp.47-62
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• 1996

The bedding zone which influence directly to the safety of dam is supporting the face slab under hydraulic load in concrete faced rockfill dam. In case that leakage is developed due to various ruptured joint or cracks of face slab and etc., the bedding zone should limit the leakage by low permeability and keep the internal stability. In this study for the proper coefficient of permeability various properties, such as gradation, dry density, performance of embankment work and etc. were analysed. The results from the large scale test of permeability and density are summerized as follows : 1. Coefficient of permeability is decreased clearly by increase of dry density. 2. The particles smaller than the No.4 strive( p,) greatly influences the permeability under dry density of 2.24t 1 m3. 3. In case of C.40 and p,40%, even if dry density decreased to 2.0t/m3, the permeability coefficient is assumed to u x1-scm/s and internal stability is abtained. 4. Generally in dam construction since dry density and uniformity coefficient of bedding zone were higher than 2.2t/m3 and 50 respectively p, of 30~40% is assumed to be suitable and permeability coefficient of below 1$\times$10-3cm l s is expectable.